Kurt Bardella, the 27-year-old aide at the center of an e-mail uproar in the office of House Oversight and Government Reform Committee Chairman Darrell Issa, is known on Capitol Hill as diligent and hardworking but said to have a cocky streak — someone who promoted himself as aggressively as he promoted his boss, according to numerous Republican colleagues.

Bardella, the committee’s press secretary, was fired Tuesday as Issa conducted an internal investigation into the extent of the aide’s cooperation with Mark Leibovich, a New York Times reporter writing a book about the the culture of Washington in the contemporary age.

Even in Capitol Hill’s sea of self-promotion, Bardella stuck out. His self-bestowed nickname is “Mini-Me,” a reference to himself as an up-and-coming version of his wealthy boss.

“Kurt has had danger signs,” said a House Republican aide who refused to be named to avoid dragging other members into the storm. “If you had said, ‘X press secretary did this,’ Kurt would have been eight out of 10 people’s guess.”

Issa told POLITICO he was conducting an inquiry into whether Bardella had provided reporters’ e-mails — perhaps by forwarding or blind-copying — to Leibovich as part of the aide’s extensive cooperation with the book.

Bardella had a quick rise. He came to Capitol Hill on July 5, 2006, working first for his local congressman, Rep. Brian Bilbray (R-Calif.), then working briefly for Sen. Olympia Snowe (R-Maine) before returning to Bilbray’s office. While there, he courted the Issa team and eventually was hired.

In some ways, his job for Issa was like working for the hometown congressman — Bardella’s family is from San Diego, and Issa represents a sprawling nearby district covering parts of Riverside and northern San Diego counties. Bardella lives alone in Arlington, is a passionate fan of the Los Angeles Lakers and also roots for the New York Mets.

Friends who reached out to Bardella after this week’s news about the investigation said that he seemed poised and clinical, recognizing that he might learn one of Washington’s lessons the hard way but optimistic about whatever would come next.

Already, the revelation has had an effect on the culture of Capitol Hill. Aides say they are starting to second-guess themselves about e-mailing, and are using the phone more. Fellow aides worry about whether their e-mails were provided to Leibovich, and say they would have a hard time working with Bardella again.

“Everyone makes mistakes,” said one Republican colleague. “But usually it’s because you say something flippant to a reporter, or something like that. But this seems to have an intent behind it that adds a greater level of toxicity.”

Bardella almost lost his job in late January, after The New Yorker’s Ryan Lizza published a harsh profile of Issa that included extensive unguarded, on-the-record comments by Bardella.

“Over lunch at Bistro Bis, a French restaurant near the Capitol, Bardella was surprisingly open in his disparagement of the media,” Lizza wrote.

“He said, ‘Some people in the press, I think, are just lazy as hell. There are times when I pitch a story, and they do it word for word. That’s just embarrassing.’ … [H]e was quick to explain how he had helped transform Issa from an obscure congressman to a fixture of the Washington media-political establishment. … ‘My goal is very simple,’ he said. ‘I’m going to make Darrell Issa an actual political figure. I’m going to focus like a laser beam on the 500 people here who care about this crap.’”

Asked about an incident in which Howard Kurtz of The Daily Beast had conducted an interview with Bardella, thinking he was the congressman, Bardella told Lizza: “I think anyone who knows me well enough knows I’m far too fond of myself to abdicate my own identity in favor of someone else’s.”

After the piece appeared, Bardella seemed philosophical about the incident, and made it clear that he considered it a learning experience.

Bardella, a fellow Californian, has a familiar relationship with his boss, referring to him as “Darrell” rather than “the Chairman” or “the Congressman,” as is more typical among Hill worker bees.

Ironically, given his current straits, Bardella was successful in his goal of raising Issa’s profile and worked the press tirelessly, at all hours, seven days a week, ingratiating himself and promoting Issa and his agenda.

On the Sunday that the Lizza profile hit, Bardella tried to distract reporters by whipping up a “This Week in Oversight” e-mail filled with schedule revelations and background notes to give them a meaty story to write about the coming week. It didn’t work. Bardella’s quotes in that article became a story.